US20210230297A1

US20210230297A1 - Antibodies Useful for Detection of Human Carcinoma Antigen

Info

Publication number: US20210230297A1
Application number: US17/208,977
Authority: US
Inventors: John Codington; Priscilla Davidson; Priscilla Agbenyefia
Original assignee: Emory University
Current assignee: Emory University
Priority date: 2018-02-26
Filing date: 2021-03-22
Publication date: 2021-07-29
Also published as: US10975164B2; US20190263929A1; US11851500B2

Abstract

This disclosure relates to diagnostic assays useful to detect a carcinoma from a sample and antibodies or binding fragments thereof useful in the diagnostic tests. In certain embodiments, this disclosure relates to antibodies or fragments that bind HCA, epiglycanin, and/or fragments thereof. In certain embodiments, this disclosure relates to anti-idiotypic antibodies or fragments that bind the variable regions of antibodies that bind HCA and/or epiglycanin.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 16/285,805 filed Feb. 26, 2019, which claims the benefit of U.S. Provisional Application No. 62/635,206 filed Feb. 26, 2018. The entirety of each of these applications is hereby incorporated by reference for all purposes.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED AS A TEXT FILE VIA THE OFFICE ELECTRONIC FILING SYSTEM (EFS-WEB)

The Sequence Listing associated with this application is provided in text format in lieu of a paper copy and is hereby incorporated by reference into the specification. The name of the text file containing the Sequence Listing is 15158US_ST25.txt. The text file is 24 KB, was created on Feb. 26, 2019, and is being submitted electronically via EFS-Web.

BACKGROUND

The Human Carcinoma Antigen (HCA) was reported to be a large mucin-type antigen consistently present in the blood of humans with carcinomas, cancers that originate in epithelial tissue. Epiglycanin is the mouse counterpart of HCA. See Codington, Epiglycanin—a carcinoma-specific mucin-type glycoprotein of the mouse TA3 tumour. Glycobiology, 1992, 2(3):173-80. See also U.S. Pat. Nos. 5,808,005, 5,693,763, 5,545,532.
Codington et al. report anti-idiotypic antibodies that bind to the hypervariable region of the AE3 antibody, an anti-idiotypic epiglycanin monoclonal antibody. Cancer, 2002, 94(3):803-13. Also described are anti, anti-idiotypic antibodies that bind to the hypervariable region of the anti-idiotypic antibodies. U.S. Published Patent Application No. 2005/0272102 reports methods for the diagnosis of prostate cancer by using an antibody or antigen-binding fragment thereof, which is specific for HCA in immunoassays. However, improved methods are needed.
Palma et al. report the human epithelial carcinoma antigen recognized by monoclonal antibody AE3 is expressed on a sulfoglycolipid in addition to neoplastic mucins. Biochem Biophys Res Commun. 2011, 408(4):548-52.
References cited herein are not an admission of prior art.

SUMMARY

This disclosure relates to diagnostic assays useful to detect a carcinoma from a sample and antibodies or binding fragments thereof useful in the diagnostic tests. In certain embodiments, this disclosure relates to antibodies or fragments that bind HCA, epiglycanin, and/or fragments thereof. In certain embodiments, this disclosure relates to anti-idiotypic antibodies or fragments that bind the variable regions of antibodies that bind HCA and/or epiglycanin.
In certain embodiments, this disclosure relates to antibodies or antigen binding fragments comprising complementarity determining regions (CDRs) or consensus sequences thereof, wherein the CDRs comprise the heavy and light chain CDRs of the antibodies of or derived from the XII-24 or AX2 hybridoma. In certain embodiments, antibodies or antigen binding fragments bind the variable regions of antibodies derived from the XII-24 or AX2 hybridoma.
In certain embodiments, the CDRs comprise the light chain XII-24 variable region CDRs within
(SEQ ID NO: 1)

DILMTQSPSSMSVSLGDTVSITCHASQGISGNIGWLQQKPGKSFKGLIYH

GTNLEDGVPSRFSGSGSGADYSLTISSLESEDFADYYCVQYIQFPFTFGG

GTKLEIKR,

wherein,
CDR1 is QGISGN (SEQ ID NO: 3),
CDR2 is HGTN (SEQ ID NO: 4), and
CDR3 is VQYIQFPFT (SEQ ID NO: 5); and
the three heavy chain XII-24 variable region CDRs within QVHLKQSGAEVVRPGASLKLSCKASGYIFTDYYVHWAKQRPGQGLEWIARIYPGSGNT YYNEKFMVKATLTAESSSSTAYMELSRLTSEDSAVYFCASSLYYPLDHWGQGTSVIVSS (SEQ ID NO: 2), wherein,
CDR1 is GYIFTDYY (SEQ ID NO: 6),
CDR2 is IYPGSGNT (SEQ ID NO: 7), and
CDR3 is ASSLYYPLDH (SEQ ID NO: 8).
In certain embodiments, the CDRs comprise the light chain AX2 variable region CDRs within
(SEQ ID NO: 9)

GIVMTQSHKFMSTSIGDRVSITCKASQDVGTAVAWYQQKPGQSPKLLIFW

ASTRHTGVPDRFTGSGSGTDFTLTISNVQSEDLADYFCQHYINYPLTFGA

GTKLELK,

wherein,
CDR 1 is QDVGTA (SEQ ID NO: 11),
CDR2 is WAST (SEQ ID NO: 12), and
CDR3 is QHYINYPLT (SEQ ID NO: 13); and
the three heavy chain AX2 variable region CDRs within QVQLQQSGAELVKPGASVKLSCKASGYTFTEYTIHWVKQRSGQGLEWIGWFYPGSGSI KYNEKFKDKATLTADKYSSTVYMELSSLTSEDSAVYFCARGGYYDSFDNWGQGTTLTV SS (SEQ ID NO: 10), wherein,
CDR1 is GYTFTEYT (SEQ ID NO: 14),
CDR2 is FYPGSGSI (SEQ ID NO: 15), and
CDR3 is ARGGYYDSFDN (SEQ ID NO: 16).
In certain embodiments, this disclosure contemplates antibodies or antigen binding fragments comprising the heavy chain CDR3 and light chain CDR3 of AX2 antibodies. In certain embodiments, this disclosure contemplates antibodies or antigen binding fragments comprising the heavy chain CDR3 and light chain CDR3 of XII-24 antibodies.
In certain embodiments, this disclosure contemplates antibodies or fragments that comprise the light and/or heavy chain sequences or CDRs disclosed herein or variants thereof. In certain embodiments, the variants have greater than 50%, 60%, 70%, 80%, 90%, or 95% sequence identity or similarity to sequences disclosed herein which are still capable of specifically binding a the binding partner of interest. In certain embodiments, the variant sequences or CDRs have less than 10 or 15 amino acid substitutions. In certain embodiments, the variants have less than 2 or 3 substitutions, or have less than 4 or 5 substitutions, or have less than 6 or 7 substitutions. In certain embodiments, the variants have less than 2 or 3 conserved substitutions, or have less than 4 or 5 conserved substitutions, or have less than 6 or 7 conserved substitutions. In certain embodiments, the amino acid substitutions are not in the CDRs.
In certain embodiments, the CDR1 of the light chain has 1 or 2 substitutions. In certain embodiments, the CDR1 of the light chain has 3 or 4 substitutions. In certain embodiments, the CDR2 of the light chain has 1 or 2 substitutions. In certain embodiments, the CDR2 of the light chain has 3 or 4 substitutions. In certain embodiments, the CDR3 of the light chain has 1 or 2 substitutions. In certain embodiments, the CDR3 of the light chain has 3 or 4 substitutions.
In certain embodiments, the CDR1 of the heavy chain has 1 or 2 substitutions. In certain embodiments, the CDR1 of the heavy chain has 3 or 4 substitutions. In certain embodiments, the CDR2 of the heavy chain has 1 or 2 substitutions. In certain embodiments, the CDR2 of the heavy chain has 3 or 4 substitutions. In certain embodiments, the CDR3 of the heavy chain has 1 or 2 substitutions. In certain embodiments, the CDR3 of the heavy chain has 3 or 4 substitutions.
In certain embodiments, this disclosure contemplates using antibodies disclosed herein, e.g., XII-24 and AX2 antibodies, in immunological assays for detecting HCA in a sample. In certain embodiments, the disclosure relates to methods comprising: mixing a sample with an anti-idiotypic antibody that binds to anti-HCA antibodies providing a mixed sample; mixing the mixed sample with anti-HCA antibodies bound to a solid substrate providing immobilized anti-idiotypic antibodies and optionally immobilized HCA on the surface; labeling the anti-idiotypic antibodies; and quantitating the label on the surface. In certain embodiments, the anti-idiotypic antibodies are XII-24 antibodies, and the anti-HCA antibodies are AX2 antibodies.
In certain embodiments, this disclosure relates to methods of determining the presence of HCA in a sample comprising, providing a solid surface immobilized with an antibody that binds HCA, mixing a sample to be tested for the presence of HCA with an anti-idiotypic antibody that binds the variable regions on the surface immobilized antibody providing a test mixture; exposing the test mixture to the surface immobilized antibody under conditions such that an anti-idiotypic antibody in the sample is capable of binding surface immobilized antibody; and detecting a decrease of antibody and anti-idiotypic antibody binding indicting the presence of HCA in the sample.
In certain embodiments, this disclosure relates to kits for diagnosis of cancer. In one embodiment, the kit comprises an anti-idiotypic antibody or antigen-binding fragment thereof which binds to the variable region of an antibody that binds to HCA and suitable ancillary reagents. In certain embodiments, the kit further comprises an antibody that binds to HCA.
In certain embodiments, the kit comprises one or more of the following components: an anti-idiotypic antibody (XII-24) to the detecting antibody, anti-HCA antibody, (AX2); a suitable immobilized phase (e.g., micro titer plates, insoluble polymeric beads or particles) that can be washed and separated from a reaction mixture and are suitable for the immobilization of an antibody disclosed herein; a specific antibody (AX2 or AE3) with high affinity to HCA that can be detected using a detection method (e.g., radiation, colorimeteric, enzymatic, chemiluminecence, etc.), either directly or indirectly; a series of calibration material (calibrators) comprised of materials that emulate HCA in patient samples that can be used to establish an appropriate response curve to map detection signal into concentration of HCA; and any required blocking agents and buffers that inhibit nonspecific binding or any other signal generating reactions that are unrelated to HCA concentration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the production and the binding properties of antibody AX2 and anti-idiotypic antibody XII-24. In the mouse, epiglycanin was found to be a mixture of highly glycosylated proteins (2-% protein by weight) of the mucin type, with a long extended protein chain to which are attached many short (2 to 7 carbohydrate residues) (carbohydrate 80% by weight). An epiglycanin type of strongly acidic properties (Emorin) was isolated both by size exclusion and affinity chromatography. Emorin was used for the immunization of C57BL mice to produce anti-Emorin lymphocytes. Using procedures for the production of monoclonal antibodies (i.e., immunization, fusion of lymphocytes with mouse myeloma cells to produce hybridoma cells, selection of the hybridoma cells that secreted antibodies with the desired specificity, growth of that hybridoma cell in culture), an anti-Emorin antibody with the desired properties, AX2, was produced.

FIG. 2 illustrates the proposed HCA complex in a sample bound with potential autoantibodies (anti-HCA antibodies) that can interfere with detection methods. Although it is not intended that embodiments of this disclosure be limited by any particular mechanism, it is possible that exposure of a sample for testing the presence of HCA or Emorin with anti-idiotypic antibodies (XII-24) releases HCA to be further detected by anti-HCA/Emorin antibodies (AX2).

FIG. 3A shows the amino acid sequence of the light (K) chain (SEQ ID NO: 17) and nucleic acid sequence encoding the light (K) chain (SEQ ID NO: 18) for AX2.

FIG. 3B shows the amino acid sequence of the heavy chain (SEQ ID NO: 19) and the nucleic acid sequence encoding the heavy (SEQ ID NO: 20) chain for AX2.

FIG. 4A shows the amino acid sequence of the light (K) chain (SEQ ID NO: 21) and nucleic acid sequence encoding the light (K) chain (SEQ ID NO: 22) for XII-24.

FIG. 4B shows the amino acid sequence of the heavy chain (SEQ ID NO: 23) and the nucleic acid sequence encoding the heavy (SEQ ID NO: 24) chain for XII-24.

DETAILED DISCUSSION

Before the present disclosure is described in greater detail, it is to be understood that this disclosure is not limited to particular embodiments described, and as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described.
All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present disclosure is not entitled to antedate such publication by virtue of prior disclosure. Further, the dates of publication provided could be different from the actual publication dates that may need to be independently confirmed.
As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure. Any recited method can be carried out in the order of events recited or in any other order that is logically possible.
Embodiments of the present disclosure will employ, unless otherwise indicated, techniques of medicine, organic chemistry, biochemistry, molecular biology, pharmacology, and the like, which are within the skill of the art. Such techniques are explained fully in the literature.
It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings unless a contrary intention is apparent.
As used in this disclosure and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) have the meaning ascribed to them in U.S. patent law in that they are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. The term “comprising” in reference to a peptide having an amino acid sequence refers to a peptide that may contain additional N-terminal (amine end) or C-terminal (carboxylic acid end) amino acids, i.e., the term is intended to include the amino acid sequence within a larger peptide. “Consisting essentially of” or “consists of” or the like, when applied to methods and compositions encompassed by the present disclosure refers to compositions like those disclosed herein that exclude certain prior art elements to provide an inventive feature of a claim, but which may contain additional composition components or method steps composition components or method steps, etc., that do not materially affect the basic and novel characteristic(s) of the compositions or methods, compared to those of the corresponding compositions or methods disclosed herein. The term “consisting of” in reference to a peptide having an amino acid sequence refers a peptide having the exact number of amino acids in the sequence and not more or having not more than a range of amino acids expressly specified in the claim.
As used herein, “subject” refers to any animal, preferably a human patient, livestock, or domestic pet.
As used herein a “sample” refers to a composition taken from or originating from a subject. Examples of samples include cell samples, blood samples, serum or plasma samples, tissue samples, hair samples, semen, and urine or excrement samples.
A “heterologous” nucleic acid or amino acid sequences refer to sequences that do not naturally occur together in a natural setting depending on the context, such as, in sequence identity or the relative location of the sequences in reference to each other. For example, when a heterologous peptide is conjugated or fused to an antibody, the peptide sequence does not occur in naturally occurring antibodies or, if the sequence does occur in antibodies, the sequence does not occur naturally in the specific location when produced in the living organism. In another example, animals have different nucleic acid sequences that are distinct in sequence from other plants, bacteria, viruses, or other organisms. Inserting a gene that expresses an animal protein into a viral based vector or plasmid is heterologous because the combination of animal and viral or plasmid sequences do not exist naturally. In the case where a nucleic acid encodes the same polypeptide sequence expressed in both organisms, the nucleic acid sequences are still not naturally occurring, as codons usage in different organisms are unique.
The terms “vector” or “expression vector” refer to a recombinant nucleic acid containing a desired coding sequence and appropriate nucleic acid sequences necessary for the expression of the operably linked coding sequence in a particular host organism or expression system, e.g., cellular or cell-free. Nucleic acid sequences necessary for expression in prokaryotes usually include a promoter, an operator (optional), and a ribosome binding site, often along with other sequences. Eukaryotic cells are known to utilize promoters, enhancers, and termination and polyadenylation signals.
Protein “expression systems” refer to in vivo and in vitro (cell free) systems. Systems for recombinant protein expression typically utilize cells transfecting with a DNA expression vector that contains the template. The cells are cultured under conditions such that they translate the desired protein. Expressed proteins are extracted for subsequent purification. In vivo protein expression systems using prokaryotic and eukaryotic cells are well known. Also, some proteins are recovered using denaturants and protein-refolding procedures. In vitro (cell-free) protein expression systems typically use translation-compatible extracts of whole cells or compositions that contain components sufficient for transcription, translation and optionally post-translational modifications such as RNA polymerase, regulatory protein factors, transcription factors, ribosomes, tRNA cofactors, amino acids and nucleotides. In the presence of an expression vectors, these extracts and components can synthesize proteins of interest. Cell-free systems typically do not contain proteases and enable labeling of the protein with modified amino acids. Some cell free systems incorporated encoded components for translation into the expression vector. See, e.g., Shimizu et al., Cell-free translation reconstituted with purified components, 2001, Nat. Biotechnol., 19, 751-755 and Asahara & Chong, Nucleic Acids Research, 2010, 38(13): e141, both hereby incorporated by reference in their entirety.
A “selectable marker” is a nucleic acid introduced into a recombinant vector that encodes a polypeptide that confers a trait suitable for artificial selection or identification (report gene), e.g., beta-lactamase confers antibiotic resistance, which allows an organism expressing beta-lactamase to survive in the presence antibiotic in a growth medium. Another example is thymidine kinase, which makes the host sensitive to ganciclovir selection. It may be a screenable marker that allows one to distinguish between wanted and unwanted cells based on the presence or absence of an expected color. For example, the lac-z-gene produces a beta-galactosidase enzyme which confers a blue color in the presence of X-gal (5-bromo-4-chloro-3-indolyl-β-D-galactoside). If recombinant insertion inactivates the lac-z-gene, then the resulting colonies are colorless. There may be one or more selectable markers, e.g., an enzyme that can complement to the inability of an expression organism to synthesize a particular compound required for its growth (auxotrophic) and one able to convert a compound to another that is toxic for growth. URA3, an orotidine-5′ phosphate decarboxylase, is necessary for uracil biosynthesis and can complement ura3 mutants that are auxotrophic for uracil. URA3 also converts 5-fluoroorotic acid into the toxic compound 5-fluorouracil. Additional contemplated selectable markers include any genes that impart antibacterial resistance or express a fluorescent protein. Examples include, but are not limited to, the following genes: ampr, camr, tetr, blasticidinr, neor, hygr, abxr, neomycin phosphotransferase type II gene (nptII), p-glucuronidase (gus), green fluorescent protein (gfp), egfp, yfp, mCherry, p-galactosidase (lacZ), lacZa, lacZAM15, chloramphenicol acetyltransferase (cat), alkaline phosphatase (phoA), bacterial luciferase (luxAB), bialaphos resistance gene (bar), phosphomannose isomerase (pmi), xylose isomerase (xylA), arabitol dehydrogenase (atlD), UDP-glucose:galactose-1-phosphate uridyltransferasel (galT), feedback-insensitive α subunit of anthranilate synthase (OASA1D), 2-deoxyglucose (2-DOGR), benzyladenine-N-3-glucuronide, E. coli threonine deaminase, glutamate 1-semialdehyde aminotransferase (GSA-AT), D-amino acidoxidase (DAAO), salt-tolerance gene (rstB), ferredoxin-like protein (pflp), trehalose-6-P synthase gene (AtTPS1), lysine racemase (lyr), dihydrodipicolinate synthase (dapA), tryptophan synthase beta 1 (AtTSB1), dehalogenase (dhlA), mannose-6-phosphate reductase gene (M6PR), hygromycin phosphotransferase (HPT), and D-serine ammonialyase (dsdA).
A “label” refers to a detectable compound or composition that is conjugated directly or indirectly to another molecule, such as an antibody or a protein, to facilitate detection of that molecule. Specific, non-limiting examples of labels include fluorescent tags, enzymatic linkages, and radioactive isotopes. In one example, a “label receptor” refers to incorporation of a heterologous polypeptide in the receptor. A label includes the incorporation of a radiolabeled amino acid or the covalent attachment of biotinyl moieties to a polypeptide that can be detected by marked avidin (for example, streptavidin containing a fluorescent marker or enzymatic activity that can be detected by optical or colorimetric methods). Various methods of labeling polypeptides and glycoproteins are known in the art and may be used. Examples of labels for polypeptides include, but are not limited to, the following: radioisotopes or radionucleotides (such as ³⁵S or ¹³¹I) fluorescent labels (such as fluorescein isothiocyanate (FITC), rhodamine, lanthanide phosphors), enzymatic labels (such as horseradish peroxidase, beta-galactosidase, luciferase, alkaline phosphatase), chemiluminescent markers, biotinyl groups, predetermined polypeptide epitopes recognized by a secondary reporter (such as a leucine zipper pair sequences, binding sites for secondary antibodies, metal binding domains, epitope tags), or magnetic agents, such as gadolinium chelates. In some embodiments, labels are attached by spacer arms of various lengths to reduce potential steric hindrance.
In certain embodiments, the disclosure relates to antibodies and antigen binding fragments comprising sequences disclosed herein or variants or fusions thereof wherein the amino terminal end or the carbon terminal end of the amino acid sequence are optionally attached to a heterologous amino acid sequence, label, or reporter molecule.
In certain embodiments, the disclosure relates to vectors comprising a nucleic acid encoding an antibody or antigen binding fragment disclosed herein or chimeric protein thereof.
In certain embodiments, the vector optionally comprises a mammalian, human, insect, viral, bacterial, bacterial plasmid, yeast associated origin of replication or gene such as a gene or retroviral gene or lentiviral LTR, TAR, RRE, PE, SLIP, CRS, and INS nucleotide segment or gene selected from tat, rev, nef, vif, vpr, vpu, and vpx or structural genes selected from gag, pol, and env.
In certain embodiments, the vector optionally comprises a gene vector element (nucleic acid) such as a selectable marker region, lac operon, a CMV promoter, a hybrid chicken B-actin/CMV enhancer (CAG) promoter, tac promoter, T7 RNA polymerase promoter, SP6 RNA polymerase promoter, SV40 promoter, internal ribosome entry site (IRES) sequence, cis-acting woodchuck post regulatory regulatory element (WPRE), scaffold-attachment region (SAR), inverted terminal repeats (ITR), FLAG tag coding region, c-myc tag coding region, metal affinity tag coding region, streptavidin binding peptide tag coding region, polyHis tag coding region, HA tag coding region, MBP tag coding region, GST tag coding region, polyadenylation coding region, SV40 polyadenylation signal, SV40 origin of replication, Col E1 origin of replication, f1 origin, pBR322 origin, or pUC origin, TEV protease recognition site, loxP site, Cre recombinase coding region, or a multiple cloning site such as having 5, 6, or 7 or more restriction sites within a continuous segment of less than 50 or 60 nucleotides or having 3 or 4 or more restriction sites with a continuous segment of less than 20 or 30 nucleotides.
In certain embodiments, term “percentage of sequence identity” is calculated by comparing two optimally aligned sequences over the window of comparison, determining the number of positions at which the identical nucleic acid base (e.g., A, T, C, G, U, or I) occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison (i.e., the window size), and multiplying the result by 100 to yield the percentage of sequence identity.
In certain embodiments, sequence “identity” refers to the number of exactly matching amino acids (expressed as a percentage) in a sequence alignment between two sequences of the alignment calculated using the number of identical positions divided by the greater of the shortest sequence or the number of equivalent positions excluding overhangs wherein internal gaps are counted as an equivalent position. In certain embodiments, any recitation of sequence identity expressed herein may be substituted for sequence similarity. Percent “similarity” is used to quantify the similarity between two sequences of the alignment. This method is identical to determining the identity except that certain amino acids do not have to be identical to have a match. Amino acids are classified as matches if they are among a group with similar properties according to the following amino acid groups: Aromatic—F Y W; hydrophobic—A V I L; Charged positive: R K H; Charged negative—D E; Polar—S T N Q.
This disclosure contemplates “conservative sequence modifications” of the sequences disclosed herein, including nucleotide and amino acid sequence modifications which do not significantly affect or alter the binding characteristics of the antibody encoded by the nucleotide sequence or containing the amino acid sequence. Such conservative sequence modifications include nucleotide and amino acid substitutions, additions and deletions. Modifications can be introduced into the sequences disclosed herein by standard techniques known in the art, such as site-directed mutagenesis and PCR-mediated mutagenesis. Conservative amino acid substitutions include ones in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine, tryptophan), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine).

Antibodies

In certain embodiments, this disclosure relates to antibodies that bind human carcinoma antigen (HCA). In certain embodiments, this disclosure relates to anti-idiotypic antibodies or fragments that bind the variable regions of antibodies that bind HCA. In certain embodiments, the antibodies that bind HCA are derived from the AX2 antibody or fragments. In certain embodiments the anti-idiotypic antibodies are derived from the XII-24 antibody or fragments.
In certain embodiments, the CDRs comprise the light chain XII-24 variable region CDRs within
(SEQ ID NO: 1)

DILMTQSPSSMSVSLGDTVSITCHASQGISGNIGWLQQKPGKSFKGLIYH

GTNLEDGVPSRFSGSGSGADYSLTISSLESEDFADYYCVQYIQFPFTFGG

GTKLEIKR,

wherein,
CDR1 is QGISGN (SEQ ID NO: 3),
CDR2 is HGTN (SEQ ID NO: 4), and
CDR3 is VQYIQFPFT (SEQ ID NO: 5); and
the three heavy chain XII-24 variable region CDRs within QVHLKQSGAEVVRPGASLKLSCKASGYIFTDYYVHWAKQRPGQGLEWIARIYPGSGNT YYNEKFMVKATLTAESSSSTAYMELSRLTSEDSAVYFCASSLYYPLDHWGQGTSVIVSS (SEQ ID NO: 2), wherein,
CDR1 is GYIFTDYY (SEQ ID NO: 6),
CDR2 is IYPGSGNT (SEQ ID NO: 7), and
CDR3 is ASSLYYPLDH (SEQ ID NO: 8).
In certain embodiments, the CDRs comprise the light chain AX2 variable region CDRs within

(SEQ ID NO: 9)

GIVMTQSHKFMSTSIGDRVSITCKASQDVGTAVAWYQQKPGQSPKLLIFW

ASTRHTGVPDRFTGSGSGTDFTLTISNVQSEDLADYFCQHYINYPLTFGA

GTKLELK,

wherein,
CDR1 is QDVGTA (SEQ ID NO: 11),
CDR2 is WAST (SEQ ID NO: 12), and
CDR3 is QHYINYPLT (SEQ ID NO: 13); and
the three heavy chain AX2 variable region CDRs within QVQLQQSGAELVKPGASVKLSCKASGYTFTEYTIHWVKQRSGQGLEWIGWFYPGSGSI KYNEKFKDKATLTADKYSSTVYMELSSLTSEDSAVYFCARGGYYDSFDNWGQGTTLTV SS (SEQ ID NO: 10), wherein,
CDR1 is GYTFTEYT (SEQ ID NO: 14),
CDR2 is FYPGSGSI (SEQ ID NO: 15), and
CDR3 is ARGGYYDSFDN (SEQ ID NO: 16).
In certain embodiments, the antibodies disclosed herein are conjugated to a label, fluorescent dye, quantum dot, nanoparticle, heterologous polypeptide, an enzyme, or solid surface. In certain embodiments, the antibody is a chimeric antibody or humanized antibody.
In certain embodiments, this disclosure relates to hybridoma that produces the antibodies disclosed herein.
In certain embodiments, the disclosure relates to vectors comprising a nucleic acid sequence encoding the light chain and/or the heavy chain of an antibody disclosed herein.
In certain embodiments, the vector comprises a heterologous nucleic acid sequence or heterologous promoter or encodes a selectable marker.
In certain embodiments, this disclosure relates to expression system comprising a vector disclosed herein. In certain embodiments, the expression system is a cell.
As used herein, the term “antibody” is intended to denote an immunoglobulin molecule that possesses a “variable region” antigen recognition site. The term “variable region” is intended to distinguish such domain of the immunoglobulin from domains that are broadly shared by antibodies (such as an antibody Fc domain). The variable region comprises a “hypervariable region” whose residues are responsible for antigen binding. The hypervariable region comprises amino acid residues from a “Complementarity Determining Region” or “CDR” (i.e., typically at approximately residues 24-34 (L1), 50-56 (L2) and 89-97 (L3) in the light chain variable domain and at approximately residues 27-35 (H1), 50-65 (H2) and 95-102 (H3) in the heavy chain variable domain; Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)) and/or those residues from a “hypervariable loop” (i.e., residues 26-32 (L1), 50-52 (L2) and 91-96 (L3) in the light chain variable domain and 26-32 (H1), 53-55 (H2) and 96-101 (H3) in the heavy chain variable domain; Chothia and Lesk, 1987, J. Mol. Biol. 196:901-917). “Framework Region” or “FR” residues are those variable domain residues other than the hypervariable region residues as herein defined. The term antibody includes monoclonal antibodies, multi-specific antibodies, human antibodies, humanized antibodies, synthetic antibodies, chimeric antibodies, camelized antibodies (See e.g., Muyldermans et al., 2001, Trends Biochem. Sci. 26:230; Nuttall et al., 2000, Cur. Pharm. Biotech. 1:253; Reichmann and Muyldermans, 1999, J. Immunol. Meth. 231:25; International Publication Nos. WO 94/04678 and WO 94/25591; U.S. Pat. No. 6,005,079), single-chain Fvs (scFv) (see, e.g., see Pluckthun in The Pharmacology of Monoclonal Antibodies, vol. 113, Rosenburg and Moore eds. Springer-Verlag, New York, pp. 269-315 (1994)), single chain antibodies, disulfide-linked Fvs (sdFv), intrabodies, and anti-idiotypic (anti-Id) antibodies (including, e.g., anti-Id and anti-anti-Id antibodies to the disclosed B7-H5 antibodies). In particular, such antibodies include immunoglobulin molecules of any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2) or subclass.
In certain embodiments, antibodies disclosed herein, fragment, or heavy chain comprise a variant Fc domain. As used herein a “variant Fc domain” refers to an Fc domain engineered to comprise at least one amino acid modification relative to a wild-type Fc domain.
As used herein, a molecule is said to be able to “immunospecifically bind” a second molecule if such binding exhibits the specificity and affinity of an antibody to its cognate antigen. Antibodies are said to be capable of “immunospecifically binding” to a target region or conformation (“epitope”) of an antigen if such binding involves the antigen recognition site of the immunoglobulin molecule. An antibody that immunospecifically binds to a particular antigen may bind to other antigens with lower affinity if the other antigen has some sequence or conformational similarity that is recognized by the antigen recognition site as determined by, e.g., immunoassays, but would not bind to a totally unrelated antigen. Preferably, however, antibodies (and their antigen binding fragments) will not cross-react with other antigens. Antibodies may also bind to other molecules in a way that is not immunospecific, such as to FcR receptors, by virtue of binding domains in other regions/domains of the molecule that do not involve the antigen recognition site, such as the Fc region.
As used herein, the term “antigen binding fragment” of an antibody refers to one or more portions of an antibody that contain the antibody's Complementarity Determining Regions (“CDRs”) and optionally the framework residues that comprise the antibody's “variable region” antigen recognition site, and exhibit an ability to immunospecifically bind an antigen. Such fragments include Fab′, F(ab′)2, Fv, single chain (ScFv), and mutants thereof, naturally occurring variants, and fusion proteins comprising the antibody's “variable region” antigen recognition site and a heterologous protein (e.g., a toxin, an antigen recognition site for a different antigen, an enzyme, a receptor or receptor ligand, etc.). As used herein, the term “fragment” refers to a peptide or polypeptide comprising an amino acid sequence of at least 5 contiguous amino acid residues, at least 10 contiguous amino acid residues, at least 15 contiguous amino acid residues, at least 20 contiguous amino acid residues, at least 25 contiguous amino acid residues, at least 40 contiguous amino acid residues, at least 50 contiguous amino acid residues, at least 60 contiguous amino residues, at least 70 contiguous amino acid residues, at least 80 contiguous amino acid residues, at least 90 contiguous amino acid residues, at least 100 contiguous amino acid residues, at least 125 contiguous amino acid residues, at least 150 contiguous amino acid residues, at least 175 contiguous amino acid residues, at least 200 contiguous amino acid residues, or at least 250 contiguous amino acid residues.
Human, non-naturally occurring chimeric or humanized derivatives of antibodies are particularly preferred for in vivo use in humans, however, murine antibodies or antibodies of other species may be advantageously employed for many uses (for example, in vitro or in situ detection assays, acute in vivo use, etc.). A humanized antibody may comprise amino acid residue substitutions, deletions or additions in one or more non-human CDRs. The humanized antibody derivative may have substantially the same binding, stronger binding or weaker binding when compared to a non-derivative humanized antibody. In specific embodiments, one, two, three, four, or five amino acid residues of the CDR have been substituted, deleted or added (i.e., mutated). Completely human antibodies are particularly desirable for therapeutic treatment of human subjects.
Human antibodies can be made by a variety of methods known in the art including phage display methods described above using antibody libraries derived from human immunoglobulin sequences (see U.S. Pat. Nos. 4,444,887 and 4,716,111; and International Publication Nos. WO 98/46645, WO 98/50433, WO 98/24893, WO 98/16654, WO 96/34096, WO 96/33735, and WO 91/10741). Human antibodies can be produced using transgenic mice which are incapable of expressing functional endogenous immunoglobulins, but which can express human immunoglobulin genes. For example, the human heavy and light chain immunoglobulin gene complexes may be introduced randomly or by homologous recombination into mouse embryonic stem cells. Alternatively, the human variable region, constant region, and diversity region may be introduced into mouse embryonic stem cells in addition to the human heavy and light chain genes. The mouse heavy and light chain immunoglobulin genes may be rendered non-functional separately or simultaneously with the introduction of human immunoglobulin loci by homologous recombination. In particular, homozygous deletion of the JH region prevents endogenous antibody production. The modified embryonic stem cells are expanded and microinjected into blastocysts to produce chimeric mice. The chimeric mice are then bred to produce homozygous offspring which express human antibodies. The transgenic mice are immunized using conventional methodologies with a selected antigen, e.g., all or a portion of a polypeptide.
Monoclonal antibodies directed against the antigen can be obtained from the immunized, transgenic mice using conventional hybridoma technology (see, e.g., U.S. Pat. No. 5,916,771). The human immunoglobulin transgenes harbored by the transgenic mice rearrange during B cell differentiation, and subsequently undergo class switching and somatic mutation. Thus, using such a technique, it is possible to produce therapeutically useful IgG, IgA, IgM and IgE antibodies. For an overview of this technology for producing human antibodies, see Lonberg and Huszar (1995, Int. Rev. Immunol. 13:65-93, which is incorporated herein by reference in its entirety). For a detailed discussion of this technology for producing human antibodies and human monoclonal antibodies and protocols for producing such antibodies, see, e.g., International Publication Nos. WO 98/24893, WO 96/34096, and WO 96/33735; and U.S. Pat. Nos. 5,413,923, 5,625,126, 5,633,425, 5,569,825, 5,661,016, 5,545,806, 5,814,318, and 5,939,598, which are incorporated by reference herein in their entirety. In addition, companies such as Abgenix, Inc. (Freemont, Calif.) and Medarex (Princeton, N.J.) can be engaged to provide human antibodies directed against a selected antigen using technology similar to that described above.
A “chimeric antibody” is a molecule in which different portions of the antibody are derived from different immunoglobulin molecules such that the entire molecule is not naturally occurring. Examples of chimeric antibodies include those having a variable region derived from a non-human antibody and a human immunoglobulin constant region such as antibodies that have murine variable domains and human constant domains. Chimeric antibodies include humanized antibodies, i.e., antibodies having murine CDRs but are otherwise human. The term is also intended to include antibodies having a variable region derived from one human antibody grafted to an immunoglobulin constant region of a predetermined sequences or the constant region from another human for which there are allotypic differences residing in the constant regions of any naturally occurring antibody having the variable regions, e.g., CDRs 1, 2, and 3 of the light and heavy chain. Human heavy chain genes exhibit structural polymorphism (allotypes) that are inherited as a haplotype. The serologically defined allotypes differ within and between population groups. See Jefferis et al. mAb, 1 (2009), pp. 332-338.
Smith et al. report a protocol for the production of antigen-specific chimeric human monoclonal antibodies (hmAbs) wherein antibody-secreting cells (ASCs) are isolated from whole blood collected after vaccination and sorted by flow cytometry into single cell plates. Nat Protoc. 2009, 4(3):372-84. The antibody genes of the ASCs are then amplified by RT-PCR and nested PCR, cloned into expression vectors and transfected into a human cell line. Meijer et al. report methods for isolation of human antibody repertoires with preservation of the natural heavy and light chain pairing. J Mol Biol. 2006, 358(3):764-72. Wrammert et al. report using immunoglobulin variable regions isolated from sorted single ASCs to produce human monoclonal antibodies (mAbs) that bound with high affinity. Nature. 2008, 453(7195): 667-671.
Methods for producing chimeric antibodies are known in the art. See e.g., Morrison, 1985, Science 229:1202; Oi et al., 1986, BioTechniques 4:214; Gillies et al., 1989, J. Immunol. Methods 125:191-202; and U.S. Pat. Nos. 6,311,415, 5,807,715, 4,816,567, and 4,816,397. Chimeric antibodies comprising one or more CDRs from a non-human species and framework regions from a human immunoglobulin molecule can be produced using a variety of techniques known in the art including, for example, CDR-grafting (EP 239,400; International Publication No. WO 91/09967; and U.S. Pat. Nos. 5,225,539, 5,530,101, and 5,585,089), veneering or resurfacing (EP 592,106; EP 519,596; Padlan, 1991, Molecular Immunology 28(4/5):489-498; Studnicka et al., 1994, Protein Engineering 7:805; and Roguska et al., 1994, Proc. Natl. Acad. Sci. USA 91:969), and chain shuffling (U.S. Pat. No. 5,565,332).
As used herein, the term “humanized antibody” refers to an immunoglobulin comprising a human framework region and one or more CDR's from a non-human (usually a mouse or rat) immunoglobulin. The non-human immunoglobulin providing the CDR's is called the “donor” and the human immunoglobulin providing the framework is called the “acceptor.” Constant regions need not be present, but if they are, they must be substantially identical to human immunoglobulin constant regions, i.e., at least about 85-90%, preferably about 95% or more identical. Hence, all parts of a humanized immunoglobulin, except possibly the CDR's, are substantially identical to corresponding parts of natural human immunoglobulin sequences. A humanized antibody is an antibody comprising a humanized light chain and a humanized heavy chain immunoglobulin. For example, a humanized antibody would not encompass a typical chimeric antibody, because, e.g., the entire variable region of a chimeric antibody is non-human. One says that the donor antibody has been “humanized,” by the process of “humanization,” because the resultant humanized antibody is expected to bind to the same antigen as the donor antibody that provides the CDR's. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which hypervariable region residues of the recipient are replaced by hypervariable region residues from a non-human species (donor antibody) such as mouse, rat, rabbit or a non-human primate having the desired specificity, affinity, and capacity. In some instances, Framework Region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies may comprise residues which are not found in the recipient antibody or in the donor antibody. These modifications are made to further refine antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable regions correspond to those of a non-human immunoglobulin and all or substantially all of the FRs are those of a human immunoglobulin sequence. The humanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin that immunospecifically binds to an Fc RIIB polypeptide, that has been altered by the introduction of amino acid residue substitutions, deletions or additions (i.e., mutations).
DNA sequences coding for preferred human acceptor framework sequences include but are not limited to FR segments from the human germline VH segment VH1-18 and JH6 and the human germline VL segment VK-A26 and JK4. In a specific embodiment, one or more of the CDRs are inserted within framework regions using routine recombinant DNA techniques. The framework regions may be naturally occurring or consensus framework regions, and preferably human framework regions (see, e.g., Chothia et al., 1998, “Structural Determinants In the Sequences of Immunoglobulin Variable Domain,” J. Mol. Biol. 278: 457-479 for a listing of human framework regions).
In certain embodiments, this disclosure relates to antibodies or antigen binding fragments comprising six complementary determining regions (CDRs) or consensus sequences thereof, wherein the CDRs comprise the three heavy and/or light chain CDRs of the antibody derived from the XII-24 or AX2. In certain embodiments, antibodies or antigen binding fragments bind the variable regions of antibodies derived from the AX2 hybridoma. In certain embodiments, the disclosure contemplates that any of the antibody sequences disclosed herein may be changed or contain at least one non-naturally occurring substitution modification relative to wild-type sequences or the sequence reported.
Antibodies to HCA and methods for their production have been described in U.S. Pat. Nos. 5,808,005; 5,693,763; 5,545,532. Antibodies to epiglycanin and methods for their production have also been described in the art. For example, monoclonal antibodies to epiglycanin and methods for their production are described, for example, in U.S. Pat. Nos. 4,837,171, 5,545,532, and Haavik et al., Glycobiology, 2:217-224 (1992). Hybridomas producing anti-murine epiglycanin antibodies, AE-1, AE-3 and AE-4, have been deposited with the American Type Culture Collection (ATCC), P.O. Box 1549, Manassas, Va. 20108 USA. For example, the hybridoma HAE-1 (producing monoclonal antibody AE-1) was deposited at the ATCC under accession no. HB-9466. The hybridoma HAE-3 (producing monoclonal antibody AE-3) was deposited at the ATCC under accession no. HB-9467. The hybridoma HAE-4 (producing monoclonal antibody AE-4) was deposited at the ATCC under accession no. HB-9468. Monoclonal antibody AE-3 cross-reacts and binds with HCA.
In practice, a monoclonal antibody is an antibody derived from a single hybridoma cell, after cloning. Thus, all hybridoma cells from a particular hybridoma cell inherit the same specificity. They are monoclonal. A good example is the experiment that produced that produced the AE-1, AE-3, and AE-4 monoclonal antibodies. These were all produced after immunization with the heterogeneous, but structurally-related, mixture of glycoproteins, which is epiglycanin. Epiglycanin contains many epitopes, each capable of producing a lymphocyte of a specific activity. After fusion of the lymphocytes with mouse myeloma (cancer) cells, to form hybridoma cells, each now having a single specificity (from a single myeloma cell), the mixture was cloned, and a new culture, each with a single specificity was established from each successful hybridoma cell (each culture produces a new monoclonal antibody). Each of the three monoclonal antibodies resulting from that experiment (AE-1, AE-3, and AE-4) possesses a different specificity. The AX2 antibody, which was recently produced in a separate experiment, resulted from the immunization of a C57BL mouse with a purified epiglycanin, Emorin, a glycoprotein component of the epiglycanin mixture. The resulting antibody, AX2, has good stability and strong binding activity for HCA.
Antibodies can be polyclonal or monoclonal, and the term “antibody” is intended to encompass both polyclonal and monoclonal antibodies. The terms polyclonal and monoclonal refer to the degree of homogeneity of an antibody preparation, and are not intended to be limited to particular methods of production. The term “antibody”, as used herein, also encompasses functional fragments of antibodies, including fragments of human, chimeric, humanized, primatized, veneered or single chain antibodies. Functional fragments include antigen-binding fragments specific for HCA. Antigen-binding fragments specific for HCA include, but are not limited to, Fab, Fab′, F(ab′)₂and Fv fragments. Such fragments can be produced by enzymatic cleavage or recombinant techniques. For example, papain or pepsin cleavage can generate Fab or F(ab′)₂fragments, respectively. Other proteases with the requisite substrate specificity can also be used to generate Fab or F(ab′)₂fragments. Antibodies can also be produced in a variety of truncated forms using antibody genes in which one or more stop codons has been introduced upstream of the natural stop site. For example, a chimeric gene encoding a F(ab′)₂heavy chain portion can be designed to include DNA sequences encoding the CH₁domain and hinge region of the heavy chain.
Single chain antibodies, and chimeric, humanized or primatized (CDR-grafted), or veneered antibodies, as well as chimeric, CDR-grafted or veneered single chain antibodies, comprising portions derived from different species, and the like are also contemplated by the present disclosure. The various portions of antibodies can be joined together chemically by conventional techniques, or can be prepared as a contiguous protein using genetic engineering techniques. For example, nucleic acids encoding a chimeric or humanized chain can be expressed to produce a contiguous protein. See, e.g., Cabilly et al., U.S. Pat. No. 4,816,567; Cabilly et al., European Patent No. 0 125 023 B1; Boss et al., U.S. Pat. No. 4,816,397; Boss et al., European Patent No. 0 120 694 B1; Neuberger et al., International Publication No. WO86/01533; Neuberger et al., European Patent No. 0 194 276 B1; issued to Winter et al., U.S. Pat. No. 5,225,539; issued to Winter et al., European Patent No. 0 239 400 B1; Queen et al., European Patent No. 0 451 216 B1; and Padlan et al., EP 0 519 596 A1. See also, Newman et al., BioTechnology, 10: 1455-1460 (1992), regarding primatized antibody, and Ladner et al., U.S. Pat. No. 4,946,778 and Bird et al., Science, 242:423-426 (1988)) regarding single chain antibodies.
An “antigen” is a molecule or a portion of a molecule capable of being bound by an antibody which is additionally capable of inducing an animal to produce antibody capable of binding to an epitope of that antigen. An antigen can have one or more than one epitope.
The term “epitope” is meant to refer to that portion of the antigen capable of being recognized by and bound by an antibody at one or more of the antibody's antigen binding region. Epitopes usually consist of chemically active surface groupings of molecules such as amino acids or sugar side chains and have specific three dimensional structural characteristics as well as specific charge characteristics.

Immunological Assays for Detecting HCA in a Sample

It has been discovered that HCA, as well as its counterpart in the mouse, i.e., the active component of the epiglycanin mixture of mucin-type glycoproteins reported herein as Emorin, exists in the blood of subjects not as free glycoproteins but as their antibody complexes. This disclosure relates to antibodies (AX2 and XII-24) used in the detection of the Human Carcinoma Antigen (HCA) (in humans) and Emorin (in the mouse), both found as antibody complexes in body fluids. The detection of the complex, performed by the DOC (Detection of Carcinoma) Assay provides a highly sensitive method for the determination of the presence of a carcinoma in humans.
Disclosed herein is a clinical test for cancer present in epithelial tissue (i.e., carcinomas). This includes many common cancers, such as breast, prostate, lung, kidney and colon, as well as those more difficult to detect, such as pancreas and ovarian cancer. A carcinoma is indicated by the presence of the Human Carcinoma Antigen (HCA)-anti-HCA in the blood (HCA-anti-HCA complex).
The test involves a competition for the HCA between one of the monoclonal antibodies coating the plate (AX2) and the other monoclonal antibody (XII-24) in solution with the sample, e.g., serum, being tested. The results are recorded as the percent of the amount of HCA in the serum relative to the amount in a positive or negative control. The assay is capable of distinguishing between carcinoma patients and normal persons with high accuracy.
Methods disclosed herein for the detection of HCA use a sample. In certain embodiments, sample materials may include bodily fluids including plasma, serum, whole blood, spinal fluid, semen, vaginal fluids, sputum and saliva, cerebrospinal fluid, lymphatic fluid and digestive fluids. Other sample materials may include isolated or enriched cell populations and tissues. Samples may be fresh or fixed (preserved). Fixed samples may be embedded (for example, paraffin embedded).
In certain embodiments, this disclosure contemplates using antibodies disclosed herein, e.g., XII-24 and AX2 antibodies, in immunological assays for detecting HCA in a sample. In certain embodiments, this disclosure relates to methods of determining the presence of HCA in a sample comprising, providing a solid surface immobilized with an antibody that binds HCA, mixing a sample to be tested for the presence of HCA with an anti-idiotypic antibody that binds the variable regions on the surface immobilized antibody providing a test mixture; exposing the test mixture to the surface immobilized antibody under conditions such that anti-idiotypic antibody in the sample is capable of binding surface immobilized antibody; and detecting a decrease of antibody and anti-idiotypic antibody binding, indicting the presence of HCA in the sample.
In certain embodiments, this disclosure relates to methods of determining the presence of antigen in a sample, wherein the antigen is suspected to contain autoantibodies comprising, mixing a sample to be tested for the presence of antigen having autoantibodies with an anti-idiotypic antibody that binds the variable regions on the autoantibodies providing a test mixture that liberates the antigen; exposing the test mixture anti-antigen antibodies; and detecting the binding of anti-antigen antibodies to the antigen.
In certain embodiments, this disclosure relates to uses of antibodies disclosed herein in an immunological assays to detect HCA. In certain embodiments, this disclosure relates to methods comprising mixing an anti-idiotypic antibody disclosed herein with antibody that binds HCA or epiglycanin under conditions such that the anti-idiotypic antibody binds to the variable region of the antibody that binds HCA or epiglycanin.
In certain embodiments, this disclosure relates to methods for diagnosis of cancer in a human subject comprising determining the level of HCA in a sample from the subject; and comparing the level determined to the level of HCA in a control sample.
Typically, a control sample is one supplied with the kit, such as a serum sample selected from a panel of sera from healthy persons who consistently give 0.0 percent inhibition in the DOC Assay. The level of HCA in a subject's serum is defined as Percent Inhibition.
% Inhibition=Absorbance at 405 nm of:
Control Serum minus Subject Serum
Divided by: Control Serum×100
(Control Serum−Subject Serum)/(Control Serum)×100
In certain embodiments, this disclosure relates to methods for the diagnosis of cancer (carcinomas) in a human subject comprising contacting a sample (serum) from the subject with an antibody, (see FIG. 2), which will also cleave the HCA-anti-HCA complex.
Serum of free HCA has been found in the human (or a counterpart, such as Emorin, in the mouse). Thus, the DOC Assay, as described herein, determines the level of HCA in the HCA-anti-HCA antibody (HCA-anti-HCA) complex in carcinoma patients. In certain embodiments the presence of the HCA-anti-HCA in the serum of a subject (if the subject is affected with a carcinoma), may be detected for the HCA by incubating the sample with the anti-idiotypic antibody (XII-24), (or under different circumstances, with the anti-Emorin antibody AX2) (see FIG. 2) by cleaving the HCA-anti-HCA complex. The liberated HCA is then contacted by the XII-24 antibody to bind at the Fc region of the XII-24 antibody, leaving its hypervariable region free to bind to the hypervariable region of the AX2 antibody coating the surface of the plate. For the control serum, wherein there is no HCA complex, and, therefore there is no lost XII-24, the percent inhibition would be 0%. The difference in absorbance at 405 nm between the subject serum and the control serum, as expressed in percent terms, is a measure of the HCA present, any value above 0% inhibition is indicative of a carcinoma.
Immunoassays are any assays that can detect the binding (or absence of binding) of an antigen to an antibody or antigen-binding fragment and quantitate the presence of the antigen in the sample. Examples of suitable immunoassays include sandwich assays, radioimmunoassays and, preferably, competitive inhibition assays. The use of the term “antigen” or “inhibitor” in the context of a reagent in the assay is intended to include HCA, as well as functional variants and portions of HCA. An inhibitor, as used herein, refers to an antigen that is immunologically cross-reactive with HCA.
Generally, fragments or portions of HCA include those having a deletion (i.e., one or more deletions) of an amino acid (i.e., one or more amino acids) relative to the native (wildtype) HCA, respectively (such as N-terminal, C-terminal or internal deletions). Fragments or portions in which only contiguous amino acids have been deleted or in which non-contiguous amino acids have been deleted relative to native (wildtype) HCA are also envisioned.
In a radioimmunoassay (MA), the amount of antigen present in a sample is measured indirectly employing a limited amount of antibody (or antigen-binding fragment) to compete for labeled antigen. In an IRMA (immunoradiometric assay), antigen is assayed directly by reacting the antigen with excess labeled antibody (or antigen-binding fragment).
In one class of IRMA assays, the unknown antigen is insolubilized and reacted with labeled antibody (or antigen-binding fragment). When the antigen is insolubilized by reaction with solid-phase antibody (or antigen-binding fragment), the assay is termed a “two-site IRMA”, “junction test”, or “sandwich assay”. Sandwich assays are further classified according to their methodology as forward, reverse or simultaneous sandwich assays.
In a forward sandwich immunoassay, a sample containing the antigen can be first incubated with a solid-phase immunoadsorbent containing immobilized antibody (or antigen-binding fragment). Incubation is continued for a sufficient period of time to allow antigen in the sample to bind to immobilized antibody (or antigen-binding fragment) on the solid-phase immunoadsorbent. The solid-phase immunoadsorbent can then be separated from the incubation mixture and washed to remove excess antigen and other substances which also may be present in the sample. The solid-phase immunoadsorbent containing antigen (if any) bound to immobilized antibody (or antigen-binding fragment) can be subsequently incubated with labeled antibody (or antigen-binding fragment) capable of binding to the antigen. After the second incubation, another wash is performed to remove unbound labeled antibody (or antigen-binding fragment) from the solid-phase immunoadsorbent thereby removing non-specifically bound labeled antibody (or antigen-binding fragment). Labeled antibody (or antigen-binding fragment) bound to the solid-phase immunoadsorbent is then detected and the amount of labeled antibody (or antigen-binding fragment) detected can serve as a direct measure of the amount of antigen present in the sample. Such forward sandwich assays are described in the patent literature, and in particular, in U.S. Pat. Nos. 3,867,517 and 4,012,294, issued to Chung-Mei Ling, which are incorporated herein by reference.
In a reverse sandwich assay, a sample can be incubated with labeled antibody (or antigen-binding fragment) after which the solid-phase immunoadsorbent containing immobilized antibody (or antigen-binding fragment) is added and incubated. A washing step can be performed after the second incubation period. A reverse sandwich assay has been described in the patent literature in U.S. Pat. No. 4,098,876, issued to Roger N. Piasio et al.
In a simultaneous sandwich assay, a sample can be incubated simultaneously in one-step with both an immunoadsorbent containing immobilized antibody (or antigen-binding fragment) for the antigen and labeled antibody (or antigen-binding fragment) for the antigen. Thereafter, labeled antibody (or antigen-binding fragment) bound to the immunoadsorbent can be detected as an indication of the amount of antigen present in the sample. A simultaneous sandwich assay has been described in the patent literature in U.S. Pat. No. 4,837,167, issued to Hubert J. P. Schoemaker et al.
Many solid-phase immunoadsorbents can be employed. Well-known immunoadsorbents include beads formed from glass polystyrene, polypropylene, dextran, and other materials. Preferably, the solid support is a plate, stick, tube or foam or coated with such materials; etc. The antibody (or antigen-binding fragment) can be either covalently or physically bound to the solid-phase immunoadsorbent by techniques such as covalent bonding via an amide or ester linkage or adsorption.
A competitive inhibition immunoassay can be employed to determine the presence of an antigen in a sample by measuring the inhibition of formation of a competitive inhibitor-antibody (or competitive inhibitor-antigen-binding fragment) complex, one of which is typically bound and the other of which is typically labeled, by free antigen in the sample. In addition, a typical quantitative immunoassay kit can include a standardized sample of pure inhibitor, such as an antigen, so that a reference solution can be run together with the sample to minimize sampling errors and to assure precision.
Competitive immunoassays (e.g., radioimmunoassay (MA), enzyme-linked immunoadsorbant assay (ELISA)) are used to detect and quantitate the presence of antigen in a sample by determining the extent of inhibition by the antigen of a competitive inhibitor/antibody (or competitive inhibitor/antigen-binding fragment) reaction. Typically, either the inhibitor or the antibody (or antigen-binding fragment) is bound to a solid support (as described above), while the other component of the pair is labeled in some fashion to render it detectable. Methods that are used to detect and quantitate the presence of antigen in a sample are also referred to as serologic diagnostic methods.
Labels include, e.g., radionuclides (e.g., Florine-18, Tc-99m, Iodine-125, Iodine-131, Indium-111, Bismuth-210), enzymes which produce an absorptive or fluorescent detector group when reacted with a specific substrate (e.g., horseradish peroxidase, N-methylumbelliferone-o-D-galactosidase), dyes (chromophores), fluorescent compounds (e.g., fluorescein, rhodamine, phycoerythrin, cyamine dyes, other compound emitting fluorescence energy), electron dense compounds (e.g., gold and ferric chloride compounds). Biotin/avidin labeling systems can also be used. Coupled assays can also be used for detecting labels.
The label may be directly linked to the component (the inhibitor or antibody) or may be bound to it indirectly, e.g., by attaching the label to another molecule capable of recognizing a component of the antigen/antibody pair. For example, an antibody (or antigen-binding fragment) can be indirectly labeled by attaching an enzyme, fluorescent marker or radionuclide to an isotype-specific antibody which recognizes the non-variable region of the antigen-specific antibody (or antigen-binding fragment). In another embodiment, the label can be attached to an antibody (or antigen-binding fragment) which recognizes an available epitope of the antigen after it has been bound to the specific antibody (or antigen-binding fragment).
In one embodiment, the label is a dye (such as, nitrophenyl) attached to the unbound component or reagent (unbound inhibitor or antibody) via a phosphate linker. After incubation of the labeled component with the immobilized binding partner, the presence of binding can then be determined by subjecting the solid support to a phosphatase enzyme, causing hydrolysis of the dye. The presence (and amount) of the dye can then be measured by absorbance, indicating the amount of binding of the two components.
In each assay, the sample, antibody (or antigen-binding fragment) and, optionally, the inhibitor is incubated under conditions and for a period of time sufficient to allow antigen to bind to the antibody (or antigen-binding fragment), i.e., under conditions suitable for the formation of a complex between the antigen and antibody (or antigen-binding fragment). In general, it is usually desirable to provide incubation conditions sufficient to bind as much antigen or inhibitor as possible because this maximizes the binding of labeled antibody or antigen-binding fragment) to the antigen thereby increasing the signal. Suitable temperatures are generally below the temperature at which denaturation can occur.
The presence of an increased (elevated) level of HCA reactivity (found as complex with its antibody) in a sample obtained from a subject can be indicative of malignancy associated with cancer. Measurement of HCA in a sample can provide early diagnosis of prostate cancer and the opportunity for early treatment.
Suitable antibodies, and antigen-binding fragments thereof, for use in determining the presence of HCA bind to the antigen HCA. Such antibodies include antibodies to HCA, as well as antibodies to epiglycanin that cross-react and bind HCA.

Kits

Kits for use in detecting the presence of HCA in a sample can also be prepared. Such kits can include an antibody, anti-idiotypic antibody, or antigen-binding fragment disclosed herein, as well as one or more ancillary reagents. The antibody or antigen binding fragment compositions can be provided in lyophilized form, either alone or in combination with additional antibodies specific for other epitopes. The antibodies or antigen-binding fragments, which can be labeled or unlabeled, can be included in the kits with adjunct ingredients (e.g., buffers, such as Tris, phosphate and carbonate, stabilizers, excipients, biocides and/or inert proteins, e.g., bovine serum albumin). For example, the antibodies or antigen-binding fragments can be provided as a lyophilized mixture with adjunct ingredients, or adjunct ingredients can be separately provided for combination by the user. Where a second antibody or antigen-binding fragment which binds HCA is employed, such antibody or fragment can be provided in the kit, for instance in a separate vial or container. The second antibody or fragment, if present, is typically labeled, and can be formulated in an analogous manner with the antibody or fragment formulations described above. The components (e.g., antibody, ancillary reagent) of the kit can be packaged separately or together within suitable containment means (e.g., bottle, box, envelope, tube). When the kit comprises a plurality of individually packaged components, the individual packages can be contained within a single larger containment means (e.g., bottle, box, envelope, tube). Since the HCA and anti-HCA antibody complex are heat sensitive, materials containing the HCA complex, all control sera, and all antibodies should be conveniently shipped in dry ice filled insulated containers, e.g., styrofoam containers.
In a particular embodiment, the kit comprises: (a) an immobilized antigen that is comprised of either HCA, epiglycanin, an idiotypic antibody (XII-24) to the detecting antibody (AE3 or AX2) or a surrogate antigen that has a similar affinity as HCA; (b) a suitable immobilized phase (e.g., micro titer plates, insoluble polymeric beads or particles) that can be washed and separated from a reaction mixture and are suitable for the immobilization of the an antibody or antigen; (c) a specific antibody (AX2 or AE3) with high affinity to HCA that can be detected using a detection method (e.g., radiation, colorimeteric, enzymatic, chemiluminecence, etc.), either directly or indirectly; (d) a series of calibration material (calibrators) comprised of materials that emulate HCA in patient samples that can be used to establish an appropriate response curve to map detection signal into concentration of HCA; and (e) any required blocking agents and buffers that inhibit nonspecific binding or any other signal generating reactions that are unrelated to HCA concentration. The calibrators of step (d) are stable over the useful lifetime of the kit.
In certain embodiments, this disclosure relates to kits for diagnosis of cancer. In one embodiment, the kit comprises an anti-idiotypic antibody or antigen-binding fragment thereof which binds to the variable region of an antibody that binds to HCA and suitable ancillary reagents. In certain embodiments, the kit further comprises an antibody that binds to HCA.
In certain embodiments, the kit comprises one or more of the following components: an anti-idiotypic antibody (XII-24) to the detecting antibody (AX2); a suitable immobilized phase (e.g., micro titer plates, insoluble polymeric beads or particles) that can be washed and separated from a reaction mixture and are suitable for the immobilization of an antibody disclosed herein; a specific antibody (AX2 or AE3) with high affinity to HCA that can be detected using a detection method (e.g., radiation, colorimeteric, enzymatic, chemiluminecence, etc.), either directly or indirectly; a series of calibration material (calibrators) comprised of materials that emulate HCA in patient samples that can be used to establish an appropriate response curve to map detection signal into concentration of HCA; and any required blocking agents and buffers that inhibit nonspecific binding or any other signal generating reactions that are unrelated to HCA concentration.

Examples

DOC (Detection of Carcinoma) Assay

A test sample having HCA typically contains autoantibody complexes that interferes with direct antibody measurements to HCA with an anti-HCA antibody such as AX2. The HCA is present in the serum of cancer patients not as the free serum, but as the HCA-anti-HCA complex. Thus, a preferred assay method disclosed herein is to use an anti-idiotypic antibody such as XII-24 to break up these complexes and exposure to antibodies that directly bind HCA. Cleavage and binding reactions is likely a one step process.
Cleavage made by the XII-24 antibody is illustrated in FIG. 2. A major reduction in the amount of interfering material occurs when the XII-24 antibody is used instead of direct exposure to AX2, as in the protocol below.
Disclosed is a robust and accurate assay, for use in the clinic, to detect, from 60 micro liters of blood, the presence of cancers of epithelial tissue (carcinomas) at either their early or late stages. Described herein is a competitive binding assay, which involves the use of two monoclonal antibodies derived from a cancer specific component, Emorin, of the epiglycanin glycoproteins. Emorin can be isolated from the epiglycanin mixture in two ways: size-exclusion chromatography and affinity chromatography.
The first monoclonal antibody, AX2, is produced by fusion of antibody-producing B cells from a C57BL mouse immunized with an epiglycanin carcinoma specific fraction (Emorin) and mouse myeloma (tumor) cells. This antibody is specific for the carcinoma-specific epitope in epiglycanin. It is an IgM.
The second monoclonal antibody was produced by the same general methodology. Immunization of a C57BL mouse was followed by fusion of the B cells from the spleen with mouse myeloma cells. The clone was selected for its specificity for the antibody-binding site (hypervariable region) in AX2. This antibody, XII-24, is an anti-idiotypic antibody. Immunologically it is similar in cancer specificity to Emorin. It is an IgG (2a) type antibody. FIG. 1 illustrates the relationship between the two antibodies and epiglycanin.
The rationale for producing an anti-idiotypic antibody resulted from the instability of Emorin. Both AX2 and XII-24 are quite stable, and this contributes to the robust character of the assay. The idiotypic activity of XII-24 enables binding from HCA to AX2, i.e., leaving the hypervariable region of XII-24 free to bind to the hypervariable region of AX2 on the plate.
The assay is performed in a 96-well immune plate (Immulon 2 B which is a high binding surface to provide increased binding of hydrophilic proteins and complexes). It consists of seven steps. Each step is performed on a rotary shaker at about 4° C. Each step is performed in the order as described below. Serum samples to be tested are kept frozen until thawed for use (then kept at 4° C.
Step 1. The wells are coated with a PBS solution (pH 7.75) containing AX2 antibody (125 ng per 100 μl per well) and the plate is incubated for 18-24 hours. The plate is washed 3 times (W3X). The procedure can be adapted for beads. In addition to the wells to be tested, each plate has wells reserved for control sera. Two wells: from a person without evidence of disease, zero present inhibition in the DOC assay and from a control patient with a documented carcinoma.
Step 2. To prevent additional non-specific absorption of the test sample, the wells in the plate with are further blocked by the addition of 250 μl of a solution of Aqua Block at 100% concentration (East Coast Bio, New Brunswick, Me.), and the plate is allowed to incubate for 2.0 hours. (W3X).
Step 3. In separate tubes the sera to be tested are incubated with the XII-24 antibody and neutralizing antibodies to remove interfering antibodies for 14-18 hours. The neutralizing antibodies are goat anti-mouse IgG(Fc) and goat anti-human IgG and lgM. During this period two events occur. One, the XII-24 in the wells cleaves the HCA-anti-HCA complex forming the XII-24-anti-HCA antibody complex and reducing the concentration of XII-24 available for binding to the AX2 on the plate. Two, the neutralizing antibodies eliminate the activity of the interfering antibodies from the serum.
Step 4. Each solution, which contained (if cancer the HCA-anti-HCA complex and the XII-24 antibody, and which now contains less of that antibody due to the XII-24's reaction with the complex) is added to its appropriate well (100 μl per well). Incubation is continued on the plate for 3-5 hours. (W3X). If no complex is present for the XII-24, which is an IgG(2a) antibody, to cleave (the control sample), all of the original XII-24 is now free to bind (by their hypervariable regions) to AX2 immobilized on the plate.
Step 5. A solution of biotin-labeled goat anti-mouse immunoglobulin IgG(2a) is added to each well (100 μl per well). The plate is incubated for 1.5 hours. (W3X). The biotin labeled antibody now binds to the XII-24 part of the XII-24-AX2 complex on the plate. This is the portion of the original XII-24 remaining after its reaction with the HCA-anti-HCA in the sample. However, if no HCA is in the sample (as in a normal sample), all of the original XII-24 will bind to AX2.
Step 6. A solution of 100 μl of horseradish peroxidase-labeled Streptavidin is added to each well. After an incubation of 60 minutes, the plate is washed 4 times. The streptavidin binds biotin. The plate is allowed to warm to ambient temperature
Step 7. Following the addition of a solution of ABTS to each well, color develops in about 30 minutes. This is read in an automatic plate reader at 405 nm. If HCA is in the sera sample then the intensity of the signal will be reduced.
Below is a table wherein first row shows intensity data for samples from carcinoma (CA) (patients with prostate cancer) and sarcoma (SC) patients. The assay cannot differentiate between normal sarcomas, lymphomas, and leukemias, which are not cancers of epithelial tissue; thus, do not produce HCA. The sera from carcinoma patients have consistently lower absorbance values.


				% INHTB.
	SERUM	O.D. 405	AVG.	(SC 20)

	CA 109	514, 496	(505)	20%
	CA 110	526, 587	(557)	11%
	SC
20	591, 665	(628)
	SC 21	686, 792	(739)
	DIL	594, 607	(601)

Each kit may be supplied with one serum from a known carcinoma patient in order to affirm that the assay is performing well. A kit may also include serum from an individual with no cancer or other pathological problems.

Levels of HCA During the Course of Cancer Treatment

Described is a protocol may be used to monitor HCA during chemotherapy. The HCA-anti-HCA complex may remain in the blood after the cancer is treated. Protocol
1) Draw blood (serum) from the patient and store frozen.
2) Administer excess humanized non-toxic AX2 intravenously. Wait overnight (left in the blood are AX2-HCA and anti-HCA).
3) Collect fresh serum. Perform the DOC Assay. The free HCA or HCA-anti-HCA (freshly secreted) binds to the XII-24 antibody.

Claims

1. An anti-HCA antibody comprising the light and heavy chain CDRs of AX2 wherein,

the light chain CDR1 comprises QDVGTA (SEQ ID NO: 11), CDR2 comprises WAST (SEQ ID NO: 12), and CDR3 and QHYINYPLT (SEQ ID NO: 13); and

the three heavy chain CDR1 comprises GYTFTEYT (SEQ ID NO: 14), CDR2 comprises FYPGSGSI (SEQ ID NO: 15), and CDR3 comprise ARGGYYDSFDN (SEQ ID NO: 16).

2. The antibody of claim 1, wherein the light chain comprises GIVMTQSHKFMSTSIGDRVSITCKASQDVGTAVAWYQQKPGQSPKLLIFWASTRHTGVP DRFTGSGSGTDFTLTISNVQSEDLADYFCQHYINYPLTFGAGTKLELK (SEQ ID NO: 9) or variant thereof with greater than 50% identity.

3. The antibody of claim 1, wherein the heavy chain comprises QVQLQQSGAELVKPGASVKLSCKASGYTFTEYTIHWVKQRSGQGLEWIGWFYPGSGSI KYNEKFKDKATLTADKYSSTVYMELSSLTSEDSAVYFCARGGYYDSFDNWGQGTTLTV SS (SEQ ID NO: 10) or variants thereof with greater than 50% identity.

4. The antibody of claim 1, conjugated to a label, fluorescent dye, quantum dot, nanoparticle, heterologous polypeptide, an enzyme, or solid surface.

5. A vector comprising a nucleic acid sequence encoding the light chain and/or the heavy chain of claim 9 in operable combination with a promoter.

6. The vector of claim 5, comprising a heterologous promoter sequence or encodes a selectable marker.

7. An expression system comprising a vector of claim 5.

8. A method comprising:

mixing a sample with anti-idiotypic antibodies that bind to anti-HCA antibodies providing a mixed sample;

mixing the mixed sample with anti-HCA antibodies bound to a solid substrate providing immobilized anti-idiotypic antibodies and optionally immobilized HCA on the surface;

labeling the anti-idiotypic antibodies; and

quantitating the label on the surface.

9. The method of claim 8, wherein the anti-idiotypic antibodies comprise the light and heavy chain CDRs of XII-24 wherein,

the light chain CDR1 comprises QGISGN (SEQ ID NO: 3), CDR2 comprises HGTN (SEQ ID NO: 4), and CDR3 comprises VQYIQFPFT (SEQ ID NO: 5); and

the heavy chain CDR1 comprises GYIFTDYY (SEQ ID NO: 6), CDR2 comprises IYPGSGNT (SEQ ID NO: 7), and CDR3 comprises ASSLYYPLDH (SEQ ID NO: 8).

10. The method of claim 8, wherein the anti-HCA antibodies comprise the light and heavy chain CDRs of AX2 wherein,

11. A vector comprising a nucleic acid sequence encoding the light chain and/or the heavy chain of an anti-idiotypic antibody binding to an anti-epiglycanin antibody and in operable combination with a promoter,

wherein the anti-idiotypic antibody comprises the light and heavy chain CDRs of XII-24 wherein,

12. The vector of claim 11, comprising a heterologous promoter sequence or encodes a selectable marker.

13. The vector of claim 11, wherein the light chain comprises DILMTQSPSSMSVSLGDTVSITCHASQGISGNIGWLQQKPGKSFKGLIYHGTNLEDGVPS RFSGSGSGADYSLTISSLESEDFADYYCVQYIQFPFTFGGGTKLEIKR (SEQ ID NO: 1) or variant thereof with greater than 50% identity.

14. The vector of claim 11, wherein the heavy chain comprises QVHLKQSGAEVVRPGASLKLSCKASGYIFTDYYVHWAKQRPGQGLEWIARIYPGSGNT YYNEKFMVKATLTAESSSSTAYMELSRLTSEDSAVYFCASSLYYPLDHWGQGTSVIVSS (SEQ ID NO: 2) or variants thereof with greater than 50% identity.

15. An expression system comprising a vector of claim 11.